<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		
	</head>
	<body>
		<input type="button" value="点击" id="btn"/>
	</body>
	<script>
		var h=document.getElementsByTagName("head")[0];
		var s=document.createElement("script");
		s.setAttribute("src","../js/first.js");
		h.appendChild(s);
		
		document.getElementById("btn").onclick=function(){
			alert("您点击 了按钮");
		};
		window.setInterval(function(){
			console.log(Math.random());
		},400);
	</script>
</html>
